A growing number of community groups are also carrying out their own tests at sites popular with swimmers and other water users, including on the River Teign in Devon.
“People are worried about sewage in the river,” Stuart Reynolds, from the Friends of the River Teign (Fort) group, said.
The group has been using a real-time device that can indicate levels of pollution.
“Most of the time the river is clean, but people need to know when it’s not.
“We’re looking at ways that will hopefully provide us with that information, where people could pick up on their phone, straight away,” he added.